Patent literature 1 teaches arranging a plurality of microprocessors and local memories capable of being accessed only from respective microprocessors within a storage subsystem. According to this storage subsystem, each microprocessor executing an input/output processing of a storage device is provided with an ownership, and a cache control information necessary for performing the input/output processing of the relevant storage device is stored in a local memory of the microprocessor.
Further, patent literature 2 discloses a process related to dynamically allocating a real data storage area to a virtual storage area, wherein the real data storage area is assigned to the virtual storage area when a host write process occurs to the virtual storage area, and the address of the virtual storage area and the real storage are mapped. There is a drawback that the address mapping information required for input/output processing of the virtual storage area increases proportionally with the number and capacity of the virtual volumes, but this problem can be solved by storing the address mapping information in a memory device having inferior access performance but is inexpensive compared to local memories.